1. Small can be beautiful. Changing something as simple as a lightbulb can have a big effect, encouraging other pro-environmental behaviours, but also a positive aggregating effect: small items that are bought in vast numbers make a big difference at scale.
2. Clear regulation can support behaviour change and innovation. Where government regulation and legislation sets out a clear path, industry will follow. Innovation often comes in a rush after the initial pioneer, so one brave move can result in multiple improvements.
3. Well-established products can still develop radically given the right environment. Lightbulbs seemed for a long time to be a constant, until regulatory pressure resulted in a cascade of technological improvements.

The invention of the incandescent lightbulb brought enormous changes to the way that people lived and worked. But it was not until the oil shocks of the 1970s that the efficiency of a bulb that generates a lot of wasteful heat was questioned – as much as 95 per cent of their energy was produced as heat. As governments strove to promote energy efficiency, industrial giants invested heavily in alternative options, supported eventually by legislation to phase out wasteful lightbulbs.

Compact fluorescent lamps were the first energy-efficient bulbs to reach the market, using around 70-80 per cent less electricity than the equivalent traditional bulbs, as well as lasting almost 10 times longer.  

But consumers were unimpressed.These “eco-bulbs” were poorly designed, convoluted fluorescent tubes that rarely fitted well into existing light fittings; their cold white light and slow warm-up time was unpopular with consumers, and measurements were confusing for those used to buying bulbs by wattage. In the UK, there were even cases of people bulk-buying traditional bulbs while they were still available. Halogen briefly offered a more acceptable replacement, but efficiency was only slightly improved, and at a significantly higher price. Something new was needed.

Initially, light-emitting diodes (LEDs) were expensive. But soon they began to make major improvements in quality, design and functionality. As their uptake accelerated rapidly, so unit prices fell, and this once niche product came of age.

The modern LED has proven a game changer in reducing energy use, offering huge potential for rapid transition. Consumers like them because they instantly produce light close to natural daylight; they are good for carbon reduction because they produce very little heat. Today, LEDs cost as little as £2 and use up to 90 per cent less energy than incandescent bulbs and 60 per cent less than fluorescent lighting. Consumers shifted fast: by 2019, LEDs accounted for around 46 per cent of lighting sales globally, up from 37 per cent in 2018.

The speed and depth of the LED transition differs from nation to nation according to policy, economic environment and level of energy access. The governmental push to phase out inefficient bulbs that has supported the rise of the LED began in 2005 in Brazil and Venezuela, while the European Union, Australia and Switzerland began to phase them out in 2009.

Many governments and companies globally are now enacting policies to increase the uptake of LEDs due to their cost and energy-saving potential. The phase out in the US began in 2007 (before being suspended in 2019 by the Trump administration), and an EU directive will finally end the sale of incandescent and halogen lightbulbs forever by the end of 2021.

The successful replacement of a product deeply embedded in everyday life with a low-carbon alternative shows that rapid transition can happen through small actions taken by millions of people. There is often a feeling of hopelessness around creating a low or no-carbon economy: the scale seems huge and the obstacles too numerous for individual action to make a difference. But the success of the LED has brought the idea of sustainable change to every home in a way that few other technologies have managed.

Supporting and driving this change was robust government policy, showing how regulation can help phase out inefficient, wasteful and damaging products; this ultimately gave industry the impetus to shift production away from outdated technologies and invest in more efficient replacements. The result has been the inevitable decline of halogen and incandescent lightbulbs, creating savings across the board for businesses and consumers alike.

The rapid proliferation of LEDs is already having a marked impact on the total energy consumed by home lighting, which fell by 22 per cent between 2000 and 2012. As LEDs grab more market share, Oxford University research fellow Dr. Brenda Boardman believes this could fall by a further 90 per cent. This is important for rapid transition away from carbon – electricity for lighting consumed 13 per cent of total global energy demand in 2018, and currently accounts for around 5 per cent of annual global carbon emissions. To put those figures into perspective, the total emissions from international shipping amount to 1.7 per cent. Some estimates suggest that an overnight global switch to highly efficient LED lightbulbs could cut 1,400 million tonnes of CO2 emissions, avoiding the construction of 1,250 power stations around the world.

LEDs are still more expensive. But in the UK, the initial investment is estimated to be repaid within just three to four months: the potential savings are big for households, communities and countries alike. If every British home made the switch to LEDs, it’s estimated that each household would save an average of £40 over the course of a year; widespread adoption of LEDs in British homes would shave £2 billion off energy bills and prevent 8 million tonnes of carbon being released into the atmosphere.

And in the US, the Department of Energy estimates that LEDs could reduce national energy consumption for lighting by 29 per cent by 2025, saving households around £80 billion on their electric bills.

As we’ve seen, LEDs were not cheap when the technology was still new. One valuable boost to affordability came in 2010 in the form of the $10 million L Prize, sponsored by the US government. The challenge was for a private company to build a 60-watt replacement bulb with LEDs, using only 10 watts or less to produce 900 lumens of light; it would also have to emit a pleasing glow as judged by several standard industry measures. Philips’ global R&D team spent nearly a year on the ­project and was the only company to submit a successful design.

Despite the huge benefits of LEDs, market penetration was not as quick and easy as supporters had hoped, leading to governments stepping in to help accelerate adoption with subsidies for business installations of LEDs. Governments had an added incentive to drive the manufacturing and deployment of LEDs, with public lighting costs eating up an alarming share of municipal budgets – it’s estimated that public lighting can account for between 20 and 40 per cent of a council’s electricity bill in the USA.

Finally, thanks to the sustained action of both industrial development and legislative pressure, the price of LED lighting products fell low enough to make them affordable for billions of people. Over the past two decades, the cost of LEDs has decreased by over 20 times, with brightness improved 40 times over.

Not only has this created huge savings for consumers, it has also delivered a large chunk of carbon mitigation for governments. In India, for instance, the LED market has grown 130 fold in the space of just five years, with annual sales in 2014 amounting to 5 million bulbs before reaching 670 million bulbs by 2018. The proliferation of LEDs has resulted in 30 terawatt hours of annual energy savings, roughly enough to power 28 million Indian homes or the whole of Denmark for an entire year. At the same time, the price of an LED lightbulb has dropped from around £4.50 in 2014 to £0.78 in 2019, just five years later.

LEDs have also made solar home lighting systems cheaper, more efficient and viable in India, a country where many still lack access to grid electricity. They are also more robust than other options, less affected by moisture and being turned on and off frequently. They also contain no toxic materials, unlike the earlier eco bulbs, which contained mercury that made disposal and recycling difficult.

In hotter climates, LEDs have the added benefit of helping to keep buildings cool. Because incandescent lightbulbs lose 95 per cent of their energy input by emitting heat, widespread use meant that spaces quickly became warmer and less habitable in already stifling climates. These same spaces are also often being cooled with inefficient and polluting air conditioning units. LEDs, however, lose very little energy to heat, preventing people and buildings from heating up unnecessarily.

As we’ve seen, one of the key enabling factors for the shift to LEDs was their declining cost and the growing ability to replicate the light from existing lightbulbs, making it more appealing to consumers. Thanks to innovation within the lighting manufacturing sector, LEDs began to offer an affordable replacement to old lightbulbs but with a much longer lifespan and, eventually, even brighter light. The growing scale of production saw the cost of LED lighting drop dramatically. When LEDs first hit the British market, consumers could be expected to pay as much as £9 per bulb – today they can be less than £2. The price drop was so fast that consumers could expect a bulb to be as much as £1 cheaper in the space of just a year.

Courageous business decisions can quickly pay dividends, too. In 2006, Philips Lighting decided to move towards scaled up LED production, at a point when nearly two-thirds of their sales came from incandescent lightbulbs; such a radical shift faced huge opposition within the company and among shareholders. The move paid off, and the firm – now called Signify – sits comfortably in the top five LED manufacturers in the world, with an annual revenue of around £6 billion.

It is also worth mentioning that LED technology is not just about lightbulbs: it has created a new kind of extremely flexible light source that can be used in a huge range of products, from TV screens to materials and even drone display “fireworks”. Companies like Philips were driven to do so not just by legislative changes but by their broader potential.

Clear government legislation and guidance on efficiency, quality and phase-out also played a major role. The past decades have seen governments all over the world introduce a raft of measures on minimum quality and efficiency standards, the result of which has been the phase out of inefficient lightbulbs and manufacturing capacity shifting, creating the industrial scale required to drive down costs quickly. Under EU legislation, 2021 could see the last incandescent and halogen lightbulbs sold in Britain. There has been some discussion about whether old style lightbulbs might be reintroduced after Brexit, but industry pundits now say this is unlikely given the advances LEDs have made and the fall in their price.

LEDs also benefited from the unpopularity of the early eco-bulbs, which were ugly in design, pricey, took a while to warm up, and rarely lasted as long as promised. CLFs were a handy bridging technology, but LEDs have quickly surpassed them in benefits and affordability. And when compared to halogen lightbulbs, LEDs win hands down on cost. On average, a halogen lightbulb lasts around 2,000 hours, which is approximately two years of average use. LEDs, however, last for around 25,000 hours, delivering savings for consumers for years and years whilst also reducing physical waste.

The culmination of these factors – affordability and money saving, legislative changes and industry innovation – has led to a huge rise in the popularity of LEDs, proving that small actions, as well as big, can help to make change.